Method of making solid rubber articles



1935- v. SMITHERS METHOD OF MAKING SOLID RUBBER ARTICLES Filed April 19, 1934 INVENTOR VERNON L. SHITHERS i L UNIT PATENT OFFICE h i 1 991,470 I v v METHonoFMAKINGisoLIn teeter f IARI1OLES Vernon L.-s' it ers, Akron, Ohio ter es April i934, seem. 721,32 1? "Clamps. (01:18-59) f The present invention relates?to:the manufac- The rubber ballis-madejfrom a rawrubber ture of solid rubber articles such as balls, rings, stock which is to-=.;b,e furnished. to the amateur toys andthe like, and while the process is adapt operator in sheet form. *According tothe instrucable tor a wide range of; objects, it will be. det-ions to be given in; -c'arrying out the process, a

.. scribed more particularly with reference to the strip or ribbon;;of thisstock is cut fromthe sheet,- ,5. making of solid rubber balls. of sufficient volume to not quite, but substantially,

The purpose of the invention is to devisea fill themoldin-wh'ich the article isto b'e vul simple process whichwill adapt itself to thevulcanized. This stock is representedby-the numercanization ofrubber articles; by amateura it being a1 1..

in the manufacture of these articles as a recreawhich is indicated; at12, and forthe :purpose of tion. There is considerable diificulty in adapting distinguishing the two. stocks, they. may be colthe standard or known: commercial practises to. oreddifferently. The worker isinstructed to cut 1 the toy or-- play field in which more or .less edua a small pellet of this latter stock. from the sheet familiarize those interested in these matters with Stock No.11 is anordinaryrubber stock coma rudimentary knowledge oi the rubber art, pounded ,withany' suitable filling" ingredients, through making of simple articles .by methods sulphurand an accelerator, if desired. It should which can be used in the home or play room.- bejsuch a stock as will not deteriorateirapidly;

er articles-otsolidrubber .it is thepr'acti'se to within" it, usually in powderediorm,,amaterial make ahomogeneousmass or slug of rubber comwhich will volatilize under heat'and by expanpounded for vulcanization somewhat larger than sion .jcause a sufficient expansion' of, the whole, the mold cavityand while' vulcanization is in mass to'causethe rubber to fillktheqmoldand. progress, to follow up the mold with pressure. s eXert Slifilcient p e p the Stock 5 The solidity of the article is assured by'allowing a, 1 so that it will vulcanize as a solid mass. For this sufficient overflow of the stockand this is compurpose sodium bicarbonate, ammonium chlobined with the following up pressure. ride or other volatile ingredients may be employed. Obviously it would be impossible to adapt this f de i ed, the eXpanding, pressure exerting nished toan amateur. However, by the use of out the admixture of any r t it s bethe process here described'and shown, simple and lieved to be preferable to combine this ingredient even more or less. intricate rubber articles may be with rubber as described. It will be appreciated made by extremely simple operations'and with thatonly a small pill or pellet of the stock 2 is apparatus W e be e in the homenecessary to accomplish the results. It should 35 Inthe drawlng I e fil makmg further be mentioned that the compounding of S0116. rubber ball, as 131115 15 the Slmplest 01: hould ugh as to give a stock 1 can be m i may be taken as typlcal of the vulcanized rather rapidly with the temperatures ess. It w ll be appreciated also that the process ordinarily secured in a domestic oven 40 i ih g f in z waystnot specifically Having-cut out the pellet 2 the worker wraps 40 se or an e inven ion is no necessarily re-. stricted to the details shown and described. member or h t "i rubber 1 i untll hehas built a ball-shaped mass, wh ch is In the drawing,

necessarily somewhat rregular 1D. shape; One

Figure 1' is a side view of a pellet of. rubber v made roughly in spherical form for insertion in advantage of the process. 15 that accuracy 15 not 45 V I essential, and by crude hand operations it is posa small ball mold;

Figure 2 is a cross section of Figure slble to get satisfactory results. The pellet 2 need Figure 3 is a view of the finished article; not be in'the center o the ba o pi ce. The ad- Figure 4 is a view of a simple form of apparatus v tag f wrappin the stock 1 a u the pellet h as may b u ed in th home f r the vulis that all the gas is confined within the interior 50 V canization of the complete article; and of theball, and the consequent expansion gives Figure 5 is a cross-section through a ringmade th pr ssur n ssa y t th f rmati n'o a p rin accordance with the invention, fect ball. Were the-pellet 2 to be placed between Referring to the process illustrated particularly .llWO S abs 0r Strips of rubber there would be a i in Figures 1 to 4 inclusive: tendency for the gas to escape through the line l0 my object to devise a process which will be usable The worker. islalso "ed. with a second stock 1o 15 cation is involved, and it has been myobjectto rubberwithwhich he issupplied; 15:.

20. e In the commercial production of balls and oth- Stock; No.2 is a rubber' stock which has .mixed 20 30 method t th facilities u h as i ht, b furgredient may be in the form of small pellets with- 30 of separation of the two stocks, which result is prevented by the wrapping operation.

In Figure 3 the finished ball is shown, it being noted that the pellet 2 has expanded to a small sponge rubber center. If this ball were made as suggested above, using simply a piece of the expanding chemical the space would be hollow and smaller, but the entire ball would have the characteristics of a solid ball.

In Figure 4 a simple form of apparatus is shown. This is a frame 8 having a bed 9 and a pressure screw 10 above the bed. The mold which is seated on the bed 9 is, of course, of the requisite form to mold the finished article. It consists of upper and lower mold halves in which the cavity 12 is formed. As shown, it is essential that the cavity be slightly greater than the size of the raw stock, a space 14 being shown about the stock in the mold. The worker is instructed to make the piece of raw stock of such size as to almost fill the cavity, butto be certain that the mold is brought into close fitting relation when the pressure is applied. A metal to metal contact about the parting line of the mold is essential to correct results, only a very small amount of into the crack. This is overflow which is found in commercial practise.

Having assembled the mold in the press in the manner set forth, the worker places the assembly in an oven and proceeds to vulcanize'the article, the heat of vulcanization converting the chemical in the interior of the article to gaseous form,

by no means the usual whereby the requisite pressure is secured. Exact temperatures are not necessary but should, of course, be high enough to vulcanize the rubber.

The adaptability of the process to the making of other articles is shown by the ring illustrated in Figure 5.'- In this case a sheet of rubber of the proper size of the stock l is cut and made into a band. A small string or ribbon of the stock 2 is laid on the band, and the band is rolled into a ring surrounding the stock 2 When placed in a ring shaped mold'and the process carried out as set forth, perfect rings may be secured.

rubber finding its way It will be apparent that with a little ingenuity, the amateur, having learned the rudiments of the process, may extend his operations into a variety of articles. Dolls, figures of various kinds and shapes may be made. It is, of course, essential in making irregular figures that theexpanding material be distributed throughout the stock in such a way that the pressure within the mass will be exerted at the points necessary to cause the stock to fill out the mold cavity. All that the worker will require is sets of molds for the special purposes which he has in mind.

It is believed that by means of the process set forth an interesting and instructive form of amusement is provided. The amateur or juvenile worker will learn the rudiments of vulcanization of rubber, and the interest in this art will be created and fostered. The process is new within and of itself and is particularly adapted for the purpose in view.

What is claimed is:

The process of manufacturing solid rubber articles comprising enclosing a relatively small amount of rubber mixed with a material expansible at the heat of vulcanization in the interior of a body of compounded rubber stock, the raw material being in a solid mass, placing a mass of the material thus assembled-in a mold having a volume slightly greater than the volume of the rubber, the amount of rubber which is mixed with the expansible material being suflicient merely to cause the whole mass to fill the mold on vulcanization, closing the mold with a metal to metal contact above the division line, and vulcanizing the contents of the mold while retaining the sections of the mold in close contacting relation so that escape of any substantial portion of the rubber is prevented, whereby the expansible material will exert a compacting pressure upon the surrounding stock and cause it to expand and be compacted against the inner surface of the mold, and the finished article will be without appreciable rind.

VERNON L. SMITHERS. 

